Me: “Hello, may I help you?”

Customer: “I need binoculars.”

(I show him a selection of binoculars.)

Customer: “No, no, no. Not one of these. I want one with a magnification of fifty or so.”

Me: “I’m sorry, there are no binoculars with a magnification of fifty.”

Customer: “Are you saying I’m wrong? I’m an engineer. I have two diplomas. Two! I know how things work, thank you!”

(He grabs one of the binoculars, holds it the wrong way round and looks through it.)

Customer: “This one’s broken!”